How to Unclog a Kitchen Sink
Updated February 20, 2026
Clear a kitchen sink clog with five methods from easiest to most aggressive -- boiling water, plunging, baking soda, P-trap cleaning, and drain snaking.
Overview
Kitchen sink clogs are almost always grease, food particles, and soap residue stuck in the P-trap or the drain line just past it. Unlike bathroom clogs (hair), kitchen clogs are softer and respond well to simple methods. This guide gives you five methods from easiest to most aggressive. Try them in order -- most clogs clear with the first three, and you will rarely need to go past the P-trap.
What You'll Need
Safety First
- Never use chemical drain cleaner if you plan to plunge or open the P-trap. Chemical splashback causes serious burns. Already poured chemicals in? Do not plunge -- wait for them to clear.
- Garbage disposal? Never put your hand in. Tongs or pliers. Make sure it is off and unplugged before reaching near the opening.
- Do not pour boiling water into PVC drains if the sink is full of cold water -- thermal shock can soften the joints. Bail most of the water out first, or skip to plunging.
Step-by-Step Instructions
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Try Boiling Water First
Simplest method, often effective on grease. Boil a full kettle. Bail out standing water first. Pour boiling water directly into the drain, slow steady stream. Wait 5 minutes. If it drains, run hot tap water 2-3 minutes to flush. Repeat up to 3 times if drainage is improving.
Tip: Works best on grease that has not fully hardened. Clog from food mass (rice, pasta, potato peels)? Skip to plunging -- boiling water will not break up solids. -
Plunge the Drain
Cup plunger (flat bottom, not a flange/toilet plunger). Double-basin sink? Stuff a wet rag into the other drain to seal it -- otherwise the pressure just escapes. Fill the clogged side with 3-4 inches of water. Plunger over the drain, vigorous sharp strokes for 20-30 seconds. Pull away quickly to break suction. Repeat 4-5 times. Water starts draining? Run hot water several minutes to flush.
Tip: Petroleum jelly around the plunger rim creates a better seal against the sink surface. Makes the plunging significantly more effective. -
Use Baking Soda and Vinegar
Remove standing water. Pour 1/2 cup baking soda into the drain (push it down with a spoon). Follow with 1/2 cup white vinegar. It will fizz hard -- that reaction is breaking up grease and organic matter. Cover the opening with a wet cloth to force the reaction downward. Wait 15-30 minutes. Flush with a full kettle of boiling water. Safe for all pipe types.
Tip: Stubborn? Repeat 2-3 times. You can also let the mixture sit overnight for heavy grease buildup. Works best as a follow-up to partial success from plunging. -
Clean the P-Trap
Still clogged? Almost certainly in the P-trap (U-shaped pipe under the sink). Bucket directly underneath. Loosen the two slip-joint nuts (counterclockwise, hand or channel-locks). Lower the trap, dump into the bucket. You will find grease, food particles, sludge. Clean thoroughly with a bottle brush and hot soapy water. Check the pipe going into the wall -- if you can see the clog, pull it out with needle-nose pliers. Reassemble: hand-tighten plus a quarter turn. Run water, check for leaks.
Warning: The P-trap water will be nasty. Bucket in position before you loosen anything. Corroded nuts that will not turn? Do not force them -- PVC cracks, chrome strips. Penetrating oil and try again, or replace the whole trap assembly ($5-10). -
Snake the Drain Line
Clog is past the P-trap, in the wall pipe. With the trap off, insert a drain snake into the pipe opening. Feed the cable while turning clockwise. Resistance = clog. Keep turning and pushing to break through. Once it moves freely, pull back slowly, bringing the clog material with it. Reinstall the trap, run hot water several minutes to flush. A 25-foot hand-crank snake ($15-25) handles most kitchen clogs.
Tip: A 25-foot drain snake is a worthwhile buy -- serves you for years across sinks, tubs, and showers. Skip the cheap plastic zip strips for kitchen clogs. Those are for hair in bathroom drains, not grease and food. -
Prevent Future Clogs
Number one cause of kitchen clogs: grease. Never pour cooking oil, bacon grease, or fatty liquids down the drain. Wipe greasy pans with a paper towel before washing. Sink strainer to catch food. Run hot water 30 seconds after each use. Monthly boiling water or baking soda flush as prevention. Disposal? Always run cold water while grinding -- cold solidifies grease so the disposal chops it up instead of coating the pipes.
Tip: Enzymatic drain cleaners (Bio-Clean, Green Gobbler) use bacteria to eat organic buildup. Safe for all pipes and septic. Monthly use is the best preventive maintenance for kitchen drains.
Pro Tips
- Disposal on the clogged side of a double sink? Run it first. Many apparent clogs are just food stuck in the chamber that has not been fully ground.
- Double-basin sink: always seal the other side when plunging. Wet rag pushed firmly into the drain. Without it, all the pressure escapes and you accomplish nothing.
- Reassembling the P-trap? Make sure the washers are properly seated in the slip-joint nuts. Misaligned washer is the number one cause of post-reassembly leaks.
- Slow drainage developing over weeks? Do not wait for a full clog. Monthly boiling water or baking soda when it first slows prevents the eventual blockage.
- Keep a bucket under the sink for P-trap work. Searching for a container while water drips adds stress to an already messy job.
When to Call a Pro
Call a plumber if you have snaked 25+ feet and still have not cleared it (may be the main line, needs a motorized snake), if multiple drains are backing up at once (main line problem), if the drain connects to a septic system you suspect is full, or if the pipes under the sink are corroding and falling apart when you try to remove the trap.